Linear push plunger electrical switch with tubular shroud arc prevention means

ABSTRACT

An insulated body defines a longitudinal cavity about an axis. A contact carrier moves axially within said cavity in the manner of a piston and defines compartments at opposite sides thereof. The carrier is electrically conductive and has contacts diametrically positioned. In each compartment there are two fixed contacts aligned with the movable contacts and actuating means is operatively connected to the contact carrier. This operating means includes springs at each side of the carriers and insulating members that shroud the springs as contact separation takes place in either direction.

United States Patent Atakkaan [4 1 Oct. 17, 1972 [54] LINEAR PUSHPLUNGER ELECTRICAL 3,134,004 5/1964 Long ..200/159 R SWITCH'WITH TUBULARSHROUD ARC PREVENTION MEANS FOREIGN PATENTS OR APPLICATIONS 72 Inventor;Namik (L Amkkaan, Buffalo Grove, 318,360 1/1920 Germany ..200/ 148 A707,000 3/1965 Canada ..200/148 A Assignee: PP Electric p y PrimaryExaminer-J. R. Scott Cmcago, v Attorney-Darbo, Robertson & Vandenburgh[22] Filed: April 5, 1971 57 ABSTRACT 2: Appl. No.: 131,370 1 Aninsulated bodydefines a longitudinal cavity about an axis. A contactcarrier moves axially within said [52} "200/16 200/148 cavity in themanner of a piston and defines compartments at opposite sides thereof.The carrier is electri- 2; 33/06 Holh 15/10 cally conductive and hascontacts diametrically posi- 1 0 2? 2 tioned. In each compartment thereare two fixed contacts aligned with the movable contacts and actuating56] I References Cited means is operatively connected to the contactcarrier.

This operating means includes springs at each side of UNITED STATESPATENTS the carriers and insulating members that shroud the s rin s ascontact se aration takes lace in eithe 3,408,464 1 0/1968 Earlywine, Jr.'et a]. .200/16A p i p r 3/1937 King ..200/148AX 2,634,341 4/1953 Rosen..200/ 148 A X 6 Claims, 7 Drawing Figures g 26 gyi; 21 TQ 25 p. 3 W 2 238 29 44 4 33 5? i 223 w 46 5 T Z PATENTEDUCI I 7 I972 INVENTOR. v NAM/K0. A TA KKAAN YEMW LINEAR PUSII PLUNGER ELECTRICAL SWITCH WITH TUBULARSIIROUD ARC PREVENTION MEANS BACKGROUND AND SUMMARY OF THE INVENTIONstandards of the Underwriters Laboratories state that at lll20 voltsA.C. a switch must be able to handle normal current of 6.0 amps and acurrent inrush of 60 amps (with proportionately lower amperage ratingsat higher voltage ratings) to be classified as a heavy duty switch. Whenhandling this type of load, there is a tendency for an arc to establishbetween the fixed and movable contacts as contact separation occurs.This has necessitated a spacing of parts in a manner such that apermanent arc does not occur between two metal components within theswitch. The result has been that heavy duty switches conventionally arerather bulky. When considering a conventional switch box, for example,it has been possible only to put a single heavy duty switch in anytransverse plane of the box. There are many applications in which itwould be very desirable to get more switches in a single box.

The principal object ofthe present invention is to achieve a reductionin size of an electrical switch within the heavy dutycategory so as tomake available the ability to get more switches into a particularvolume. Thus, for example, it is possible to put two of the switches ofthe present invention side by side within the transverse plane of theconventional switch box. Size reduction'is, in part, achieved byproviding a relatively long path between contacts of opposite polarityas the contacts separate while still maintaining the advantages ofspring mounting of the contact carrier so as to insure good contactseating. I

Further objects and advantages will become apparent from the followingdescription.

DESCRIPTION OF THEDR'AWINGS FIG. 1 is a longitudinal section through anembodiment of they invention;

FIG. 2 is a transverse section taken at line 2-2 of FIG. I; y

FIG. 3 is a transverse section taken at line 3-3 of FIG. 1;

FIG. 4 is a partial section viewed as in FIG. 1, but illustrating onestage of the switch operation;

FIG. 5 is another partial section viewed the same as FIG. 1, butillustrating another stage in the switch operation;

FIG. 6 is a partial section as seen at line 6-6 of FIG. 3; and

FIG. 7 is a view of an alternative movable contact.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following disclosure is offeredfor public dissemination in return for the grant of apatent. Although itis detailed to ensure adequacy and aid understanding, this is notintended to prejudice that purpose of a patent which is to cover eachnew inventive concept therein no matter how others may later disguise itby variations in form or additions or further improvements. The claimsat the end hereof are intended as the chief aid toward this purpose, asit is these that meet the requirement of pointing out the parts,improvements, or combinations in which the inventive concepts are found.

The switch body is defined by an insulating housing 10 threaded to ametal housing 1 1. There is an enclosed internal cavity 12 which, forall practical purposes, is defined by the insulated housing 10. Moldedinto the base end 13 of the insulated housing are a pair of electricalconductors which at the cavity end define fixed contacts 14 and 15.These conductive members are internally threaded to receive screws 16and 17 for attaching wires to be in electrical connection withtherespective contacts. In an axial plane from that of the diametricallyopposed contacts 14 and 15 are a pair of conductive posts 20 and 21.These posts are embedded in portions 22 and 23 of the material fromwhich the housing 10 is formed. The screws24 and 25 threaded into thetop of posts 20 and 21 hold contact arms 26 and 27 thereon. At the endsof arms 26 and 27 are contacts 28 and 29. At the external end of posts20 and 21 are screws such as 30 for attaching wires.

An electrically conductive contactbridge or carrier 33 extendstransversely to the axis of cavity 12 and divides that cavity into twochambers 34 and 35. At the end of one of these chambers are the fixedcontacts 28 and 29, while at the end of the other chamber are fixedcontacts 14 and 15. The periphery 36 of the carrier is immediatelyadjacent the internal wall 37 of the housing that defines cavity 12 withonly a relatively small space therebetween. Thus, as the carrier 33moves in an axial direction within the cavity it functions as a piston.For example, as it moves downwardly in FIG. 1 it compresses the air(fluid) in chamber 35 and decreases the air pressure in chamber 34.Movable contacts 38 and 39 are diametrically opposed on carrier 33. Thecarrier 33 provides an electrical connection between the two contacts38, 39.

The operating apparatus for the switch comprises an external plunger 41coupled to an internal plunger 42. Plunger 42 is of an insulatingmaterial and defines an internal chamber 43 in'the end facing carrier 33with the walls thereabout being a skirt forming a shroud. A secondinsulating plunger 44 (serving as a pressure member) has a stud 45 whichprojects through carrier 33 and an internal chamber 46 on the oppositeend and facing end wall 13 of the housing thus, the wall of the plunger44 about the chamber 46 is a skirt forming a shroud. A spring 47 has oneend in chamber 43 and abutting the insulated plunger 42 with the otherend slipped over stud 45 and abutting carrier 33. A second spring 48abuts end 13 of the housing, extends within chamber 46 and abuts theinsulated plunger 44. The spring 48 is stronger than the spring 47.However, the two springs permit the carrier 33 to float so as to insurea good electrical connection between the movable contacts and the fixedcontacts which the movable contacts are against.

The contacts 28 and 29 would function as normally closed contacts, andthe contacts 14 and 15 would function as normally open contacts. Thus,inthe absence of disturbing forces, the movable contacts 38, 39 areagainst fixed contacts 28, 29, as illustrated in FIG. 1.

To initiate a switching operation, the plunger 41 is pushed axially inan inward direction. During the first stage of this movement the spring47 collapses (it being weaker than the spring 48). Thus, the insulatedplunger 42 moves down so that its end contacts the carrier plate 33, asillustrated in FIG. 4, In this position the insulated plunger 42 servesas a shroud for spring 47 and increases the effective distance in airbetween the contacts 28 and 29. Thus, as the movable contacts separate,and if an arc develops, that are will not bridge the space between thecontacts 28, 29, which would be an extremely undesirable condition.Furthermore, as the carrier 33 moves downwardly from the FIG. 4 positionthe air in chamber 35 is compressed (by the piston action) and flowsabout the periphery 36 of the carrier. This periphery is immediatelyadjacent the contacts 38, 39 so that the comparatively cool air fromchamber 35 that is pumped about the periphery of the carrier serves tocool arcs that may exist between the movable contacts and the fixedcontacts thereby aiding in extinguishing those arcs.

FIG. 5 illustrates the position of the carrier 33 when it is serving toestablish electrical contact between the two fixed contacts 14 and 15.This condition will be stable so long as the plunger 41 remains pushedin as far as it will go. Again, the springs 47, 48 permit the carrier tofloat so that good electrical contact is established between the twomovable contacts and the two respective fixed contacts. If plunger 41now is released, carrier 33 will commence to move upwardly from the FIG.5 position. Again, the insulated plunger 44 serves as a shroud for thespring 48 at the time of initial separation and thus increases theeffective distance between the diametrically opposed contacts so that anarc will not jump between them. At the same time, the carrier 33 servesas a piston to compress the air in chamber 34 so that it flows about theperiphery of the carrier and across the contacts to aid in extinguishingany arcs.

FIG. 7 illustrates an alternative embodiment in which there is a carrier33' having its periphery 36' in contact with wall 37 to more effectivelyserve as a piston. In this embodiment there is an opening 50 axiallythrough the movable contact 38' to serve as fluid communicationbetween'the chambers 34 and 35. Thus, as the carrier 33' is movedaxially, as indicated by arrow 51, the air is pumped across the carrierthrough the opening 50 to aid in extinguishing the arc.

I claim:

1. In a compact electrical switch comprising a tubular housing ofinsulating material and defining an internal cavity having alongitudinal axis, two fixed contacts at opposite sides of said axisrespectively and facing one end of said cavity, a moving contact bridgebetween said contacts and said end and movable in an axial direction insaid cavity, said bridge having contacts thereon aligned with andbearing against the respective fixed contacts, and switch actuator meansoperatively associated with said bridge for moving said bridge in anaxial direction to move the bridge contacts away from the fixedcontacts, the improvement wherein said actuator means comprises:

a coil spring coaxial with said axis and, when compressed, urging saidbridge in the direction of said one end of the cavity; and

a pressure member coaxial with said axis and having an axial chamberwithin which at least a part of the spring is received with the pressuremember forming a skirt about said chamber, said pressure member being aninsulating material, said skirt being positioned between said fixedcontacts and about the portion of the spring between the fixed contactswhen the bridge contacts are against the fixed contacts whereby as saidbridge moves toward said one end and the bridge contacts are separatingfrom the fixed contacts, that part of the spring that is diametricallybetween the contacts is shrouded by said pressure member therebyreducing the possibility that an arc will occur between the fixedcontacts;

said pressure member contacting said bridge, said chamber facing saidone end of. the cavity, said housing closing said one end of said cavitywith the spring being between said one end and the pressure member,means defining an axial stud at the other side of the bridge, a plungerat the other end of the housing and movable axially in the housing, theportion of the plunger adjacent said other side of thebridge being aninsulator and defining a second chamber facing the bridge, a second coilspring in said second chamber and in compression between the plunger andthe bridge, said second spring having a portion encircling said stud,said second spring being weaker than the spring contacting said pressuremember, and a second pair of fixed contacts between the bridge and theother end of the cavity and on opposite sides of the axis respectively,said bridge having contacts thereon facing said second pair of fixedcontacts.

2. In a compact electrical switch comprising a tubular housing ofinsulating material and defining an internal cavity having alongitudinal axis, two fixed contacts at opposite sides of said axisrespectively and facing one end of said cavity, a contact bridge betweensaid fixed contacts and said end and movable in an axial direction insaid cavity, said bridge having contacts on one side thereof, alignedwith and bearing against the respective fixed contacts, means includinga spring extending along said axis and having one, end bearing againstsaid one side of the bridge and a second end bearing against saidhousing at the other end of the cavity to resiliently urge said bridgecontacts away from said fixed contacts, a portion of said spring beingdiametrically between the fixed contacts, and a switch actuator deviceoperatively associated with said bridge for moving said bridge in anaxial direction toward said one end of said cavity to move the bridgecontacts away from the fixed contacts, the improvement comprising:

means defining an insulating shroud around said portion of the springwhereby as said bridge moves away from the fixed contacts, said shroudwill aid in preventing an are from developing between the fixedcontacts.

3. In a switch as set forth in claim 2, wherein said bridge contacts areelectrically connected to each other, and said means extending alongsaid axis includes a pressure member of insulating material, saidpressure member being between the spring and the bridge with one endthereof being in contact with the bridge, the other end of the pressuremember having a skirt defining a cavity into which an end part of thespring extends, said skirt forming said insulating shroud.

4. in a switch as set forth in claim 3, wherein said actuator deviceincludes an axially positioned plunger having an end adjacent the otherside of the bridge, said end having a cavity therein with a skirttherearound, said plunger being movable axially, an axially positionedspring bearing against the other side of the bridge and extending intosaid plunger cavity and bearing against the plunger, said switchincluding a second pair of fixed contacts spaced from said other side ofthe bridge, and a second pair of bridge contacts on said other side ofthe bridge.

5. In a switch as set forth in claim 2, wherein said actuator deviceincludes an axially positioned plunger having an end adjacent the otherside of the bridge, said end having a cavity therein with a skirttherearound, said plunger being movable axially, an axially positionedspring bearing against the other side of the bridge and extending intosaid plunger cavity and bearing against the plunger, said switchincluding a second pair of fixed contacts spaced from said other side ofthe bridge, and a second pair of bridge contacts on said other side ofthe bridge.

6. In a compact electrical switch comprising a tubular housing anddefining an internal cavity having a longitudinal axis, a first pair offixed contacts one location along said axis, a second pair of fixedcontacts at another location along said axis, a bridge positionedbetween said two pairs of fixed contacts and having contacts thereonelectrically connected to each other, said bridge being movable betweena first position at which the bridge contacts are against one pair offixed contacts and form an electrical circuit therebetween and a secondposition at which the bridge contacts are against the other pair offixed contacts and form an electrical circuit therebetween, andactuating means bearing against the bridge for moving the bridge fromsaid first to said second position and from said second position to saidfirst position, said actuating means including two springs, one of saidsprings having at least a portion thereof at one side of said bridge andbetween said one pair of contacts, the other of said springs having atleast a portion thereof at the other side of the bridge and between saidother pair of contacts, the improvement wherein said actuating meansincludes:

means defining a shroud about said portion of said one spring when thebridge is in the first position; and means defining a shroud about saidportion of said other spring when said bridge is in the second position;whereby as the bridge moves away from either position and the bridgecontacts separate from the fixed contacts there will be a shroud aboutthe respective spring to aid in preventing an are from developing whichwould include the portion of the respective spring.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIGN pa ent, 3,699,276Dated October 17, 1972 Inventor s Namik O. Atakkaan It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, line 50, a semicolon should be inserted after "housing".

Column 5, line 28, after "contacts" should be inserted --in-.

Signed and sealed this 13th day of March 1973 (SEAL) Attest:

EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents UNITED STATES PATENT oFTTcE CERTIFICATE OF CORRECTIGN PatentNo, 3,699,276 Dated October 17, 1972 Inventor(s) Namlk kkaan It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 50, a semicolon should be inserted after "housing".

Column 5, line 28, after "contacts" should be inserted --in-.

Signed and sealed this 13th day of March 1973 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

1. In a compact electrical switch comprising a tubular housing ofinsulating material and defining an internal cavity having alongitudinal axis, two fixed contacts at opposite sides of said axisrespectively and facing one end of said cavity, a moving contact bridgebetween said contacts and said end and movable in an axial direction insaid cavity, said bridge having contacts thereon aligned with andbearing against the respective fixed contacts, and switch actuator meansoperatively associated with said bridge for moving said bridge in anaxial direction to move the bridge contacts away from the fixedcontacts, the improvement wherein said actuator means comprises: a coilspring coaxial with said axis and, when compressed, urging said bridgein the direction of said one end of the cavity; and a pressure membercoaxial with said axis and having an axial chamber within which at leasta part of the spring is received with the pressure member forming askirt about said chamber, said pressure member being an insulatingmaterial, said skirt being positioned between said fixed contacts andabout the portion of the spring between the fixed contacts when thebridge contacts are against the fixed contacts whereby as said bridgemoves toward said one end and the bridge contacts are separating fromthe fixed contacts, that part of the spring that is diametricallybetween the contacts is shrouded by said pressure member therebyreducing the possibility that an arc will occur between the fixedcontacts; said pressure member contacting said bridge, said chamberfacing said one end of the cavity, said housing closing said one end ofsaid cavity with the spring being between said one end and the pressuremember, means defining an axial stud at the other side of the bridge, aplunger at the other end of the housing and movable axially in thehousing, the portion of the plunger adjacent said other side of thebridge beiNg an insulator and defining a second chamber facing thebridge, a second coil spring in said second chamber and in compressionbetween the plunger and the bridge, said second spring having a portionencircling said stud, said second spring being weaker than the springcontacting said pressure member, and a second pair of fixed contactsbetween the bridge and the other end of the cavity and on opposite sidesof the axis respectively, said bridge having contacts thereon facingsaid second pair of fixed contacts.
 2. In a compact electrical switchcomprising a tubular housing of insulating material and defining aninternal cavity having a longitudinal axis, two fixed contacts atopposite sides of said axis respectively and facing one end of saidcavity, a contact bridge between said fixed contacts and said end andmovable in an axial direction in said cavity, said bridge havingcontacts on one side thereof, aligned with and bearing against therespective fixed contacts, means including a spring extending along saidaxis and having one end bearing against said one side of the bridge anda second end bearing against said housing at the other end of the cavityto resiliently urge said bridge contacts away from said fixed contacts,a portion of said spring being diametrically between the fixed contacts,and a switch actuator device operatively associated with said bridge formoving said bridge in an axial direction toward said one end of saidcavity to move the bridge contacts away from the fixed contacts, theimprovement comprising: means defining an insulating shroud around saidportion of the spring whereby as said bridge moves away from the fixedcontacts, said shroud will aid in preventing an arc from developingbetween the fixed contacts.
 3. In a switch as set forth in claim 2,wherein said bridge contacts are electrically connected to each other,and said means extending along said axis includes a pressure member ofinsulating material, said pressure member being between the spring andthe bridge with one end thereof being in contact with the bridge, theother end of the pressure member having a skirt defining a cavity intowhich an end part of the spring extends, said skirt forming saidinsulating shroud.
 4. In a switch as set forth in claim 3, wherein saidactuator device includes an axially positioned plunger having an endadjacent the other side of the bridge, said end having a cavity thereinwith a skirt therearound, said plunger being movable axially, an axiallypositioned spring bearing against the other side of the bridge andextending into said plunger cavity and bearing against the plunger, saidswitch including a second pair of fixed contacts spaced from said otherside of the bridge, and a second pair of bridge contacts on said otherside of the bridge.
 5. In a switch as set forth in claim 2, wherein saidactuator device includes an axially positioned plunger having an endadjacent the other side of the bridge, said end having a cavity thereinwith a skirt therearound, said plunger being movable axially, an axiallypositioned spring bearing against the other side of the bridge andextending into said plunger cavity and bearing against the plunger, saidswitch including a second pair of fixed contacts spaced from said otherside of the bridge, and a second pair of bridge contacts on said otherside of the bridge.
 6. In a compact electrical switch comprising atubular housing and defining an internal cavity having a longitudinalaxis, a first pair of fixed contacts one location along said axis, asecond pair of fixed contacts at another location along said axis, abridge positioned between said two pairs of fixed contacts and havingcontacts thereon electrically connected to each other, said bridge beingmovable between a first position at which the bridge contacts areagainst one pair of fixed contacts and form an electrical circuittherebetween and a second position at which the bridge contacts areagainst the other pair of fixed contacts and Form an electrical circuittherebetween, and actuating means bearing against the bridge for movingthe bridge from said first to said second position and from said secondposition to said first position, said actuating means including twosprings, one of said springs having at least a portion thereof at oneside of said bridge and between said one pair of contacts, the other ofsaid springs having at least a portion thereof at the other side of thebridge and between said other pair of contacts, the improvement whereinsaid actuating means includes: means defining a shroud about saidportion of said one spring when the bridge is in the first position; andmeans defining a shroud about said portion of said other spring whensaid bridge is in the second position; whereby as the bridge moves awayfrom either position and the bridge contacts separate from the fixedcontacts there will be a shroud about the respective spring to aid inpreventing an arc from developing which would include the portion of therespective spring.